The invention relates to a printed circuit board arranged having a printed circuit on a carrier film serving as the carrier material. A connector strip having a large number of connection pins is disposed on the printed circuit board using surface-mounting technology.
In digital technology, connector strips surface-mounted on the printed circuit board are widespread. The connector strips comprise a plastic body containing the connector part and from which a row of connection pins project from one longitudinal side. The connector strip is connected to the printed circuit board by, for example, rivets or adhesives. The connection pins are in contact with the solder connection points provided on the printed circuit board. The solder connection points generally comprise a solder paste applied to the printed circuit board by screen printing. The firm solder connection is achieved by heating. The solder paste melts and flows around the corresponding connection pins of the connector strip. To ensure that all connection pins are in contact with the solder connection point during the soldering operation in the case of a larger connector strip with a large number of connections, the connector strip must be pressed onto the printed circuit board during heating. After cooling of the solder connection, therefore, tensions are generated between the printed circuit board and the connector strip as a result of deformation of the connection pins during pressing. The magnitude of these tensions depends on the contact pressure during soldering, on the spacing of the connection pin before soldering, and on the cross-section of the connection pin. This surface-mounted connector strip technique is however; only usable, for connectors, through which not very high currents flow and correspondingly, in which the cross-section of the connection pins is small.
In the case of circuits in the fields of power electronics or motor vehicle electronics, which require higher currents, the method described above cannot be used in series production. The reason for this is the larger cross-sections of the various connection pins. The larger cross-sections of the connection pins require a higher contact pressure during soldering of the connector for all the connection pins to be in adequate contact with the corresponding solder points during the soldering process. After cooling of the solder connection, increased tensions are generated between the connection pins and the printed circuit board on account of the large cross-sections of the connection pins. These tensions result in possible deformation of the connection pins in the plastic body or in the conductors lifting off the carrier film. In addition, deformations of the connector contacts in the plastic housing can already occur during the soldering process. For this reason, the connector strips, which must meet high current requirements, are connected to the printed circuit board by a second soldering process of the fit-through type in the case of printed circuit boards of which the electrical components are surface-mounted.
A first object underlying the invention is therefore to provide a printed circuit board having a surface-mounted connector strip that is also suitable for higher currents.
A further object of the invention is to provide a method by which a connector strip can be surface-mounted on a printed circuit board.